change to generate_a_cmd to evaluate Args first before use; also issue error messages if Cmd is not recoginisedby Wrangler.
change to generate_a_cmd to evaluate Args first before use; also issue error messages if Cmd is not recoginisedby Wrangler.

andrzejsliwa/wrangler,prowessproject/wrangler,tdb/wrangler,bsmr-erlang/wrangler,arcusfelis/wrangler,arcusfelis/wrangler